As early as 910, William of Aquitaine founded Cluny Abbey at a pivotal moment in the religious and artistic history of the Western Middle Ages. The new Abbey promoted the reform of the Benedictine Rule and, in a short time, created a vast network of monastic dependencies and affiliated houses, thus becoming one of the richest and most powerful monasteries in the Christian world.
 

Raoul Glaber, a monk and chronicler of the first millennium, said of this period: "It was as if the world itself had shaken itself and, shedding its antiquity, had clothed itself on all sides in a white robe of churches".